[libre-riscv-dev] Request for input and technical expertise for Systèmes Libres Amazon Alexa IOT Pitch 10-JUN-2020

[Hendrik Boom]

On Mon, Jun 08, 2020 at 12:13:48PM +0100, Luke Kenneth Casson Leighton wrote:
> 
> all of these things are at the architectural level.  we are not doing
> anything fancy at the gate level.  it is a matter of making
> *architectural* decisions that reduce power consumption, operating
> within the exact same gate-level power consumption constraints as
> every other ASIC out there.

You point out that the CPU and GPU share cache, being the same processor.

But we are designing a four-core chip?  To what extent to the four 
cores share cache?

And on avoiding data copying between CPU ad GPU:

I believe the OpenGL API involves copying data from CPU buffers to GPU 
buffers, with the understanding that the CPU copies can be discarded 
while the GPU goes on with its copy.

Having the same storage for both sets of buffers could obviously obviate 
these copies, except that software that uses this API will likely rely 
on being able to overwrite the CPU-side buffers with impunity.  So the 
copy will still have to be done.

Do I misunderstand OpenGL?  Is Vulcan different?  Will users want to 
bypass these libraries and use the graphics instructios directly?  Or 
is there some other sublety I'm missing? 

-- hendrik